Set your air fryer to 400°F and let it warm up for 3 to 5 minutes depending on its size.
Cut the tops off the bell peppers, remove the seeds, then chop the tops to add to the filling later.
Place the hollowed peppers in the air fryer basket and cook them for 6 minutes to soften.
While the peppers cook, heat olive oil in a large deep skillet over medium-high heat.
Add the diced onion and pepper tops to the pan and sauté until they turn soft and translucent, about 2 to 3 minutes.
Toss in the garlic and cook for another 1 to 2 minutes until aromatic.
Add ground beef to the skillet and cook thoroughly until no longer pink, reaching 160°F inside.
Stir in Italian seasoning, salt, diced tomatoes with juice, and coconut aminos or Worcestershire sauce to combine all flavors.
Mix in the uncooked rice and water, then cover and reduce heat to medium-low; let it simmer for about 15 minutes or until the rice is tender.
Once the filling is ready, spoon it evenly into each softened pepper shell.
Put the filled peppers back in the air fryer and cook at 400°F for 4 minutes.
Pause to sprinkle shredded cheese on top if using, then air fry for an additional 4 minutes until cheese melts and bubbles.
If avoiding cheese, simply air fry for 8 minutes after filling.
Serve warm and enjoy your fast and tasty air fryer stuffed peppers!